Mulch is a beneficial layer or either inorganic or organic material that is placed on top of soil to protect it from erosion, to retard weed growth and to save moisture. Rubber mulch is made entirely out of recycled rubber. Many gardeners prefer to use rubber mulch as opposed to other kinds of mulch, because it can last for years without having to be replaced.
Rubber mulch is generally composed of nuggets extracted from rubber tires, or waste tire buffings. The rubber is ground up after removal of the steel bands. Nuggets are usually three-eighths of an inch to 1 1/4 inches.
Rubber buffings and nuggets are capable of insulating soil from heat, which permits a slightly higher (two or three degrees) soil temperature difference compared to wood mulches. Since rubber is not porous, it doesn't take away water from the soil. It also decreases the growth of fungus and functions as a barrier against weeds. Weed seeds dehydrate in the mulch before they get to the soil.
Rubber mulch has greater elasticity than mulches that are plant-based. When used in thicker layers, rubber mulch offers a springy bounce, making it useful and safe for playgrounds.
Rubber mulch will not decay, mildew, mold, rot or decompose. It decreases dust and doesn't produce unpleasant composting odors or fumes. Also, rubber mulch does not attract rodents, insects or other pests.
Certain recycled kinds of rubber mulch can emit chemicals that could be dangerous to plants. Also, if ignited, rubber mulch can be potentially hazardous. Rubber is also extremely hard to extinguish.